In the packaging of snack foods as well as other products it is not uncommon for a considerable number of packaging machines and their associated weighing apparatus to receive product from a conveyor assembly. Such a packaging machine is disclosed in U.S. Pat. No. 4,663,917. Typically, the conveyor assembly will have gates along its length with product taken from each gate and delivered to an associated one of the packaging machines. These conveyors with their gate assemblies are complex. Accordingly they are generally expensive, difficult to maintain and in particular difficult to clean. This is a major issue where the product is a food.
A known type of conveyor is a slip conveyor. A slip conveyor includes a longitudinally extending tray with a surface along which the product is conveyed. The tray is longitudinally and in some instances also vertically reciprocated (oscillated) to cause the product to move from an upstream position to a downstream position on the tray. It is known to use slip conveyors in series. The trays are located so that the upstream end of one tray is located beneath the downstream end of the next adjacent upstream tray so that product is conveyed therealong. Product is removed from the conveyor assembly by displacing one of the trays so that there is no longer an overlap. Accordingly product then falls between the two adjacent trays. Such arrangements overcome the need for gates. However these arrangements have a number of disadvantages including positioning of the trays where there is a significant number of trays arranged in the assembly. In particular, if a number of trays are activated, appropriate gaps between adjacent trays may not occur.
Slip (vibratory) conveyors are described in U.S. Pat. Nos. 5,042,643, 5,494,151, 5,777,232, 5,804,733, 5,865,297, 6,044,710, 6,206,180, 6,318,542, 6,374,985 and 6,457,577, as well as U.S. patent applications 2002/0125109 and 2004/0112715 and Australian patent application 2005225102.
The conveyors described in the abovementioned USA patents and patent applications do not address the abovementioned problem associated with assemblies including a plurality of trays (conveyors).